Viscose (also known as Rayon) filaments are obtained from regenerated cellulose and are used in many different sectors mainly as reinforcement material in tires and other cord applications and in the clothing industry. The incorporation of a phosphor-containing pigment imparts flame-retardancy properties to these fibers, which then can be used as part of personal protection textiles delivering wear comfort. There are no recycling strategies for these materials being brought to landfills or chemically degraded since incineration is difficult because of their flame retardancy. In this study, an enzyme-based strategy for the recovery of glucose and of the phosphor pigment without altering their chemical structures was developed as a circular economy solution. Rayon fibers were completely hydrolyzed by a cellulase preparation while 98% of the glucose (reducing sugar assay and HPLC analysis) and more than 99% of the flame-retardant pigment present in the fibers was recovered. The recovered pigment was analyzed via 1H, 13C, and 31P NMR, and the purity >95% was comparable to that of the commercially available pigment. The recovered glucose was successfully used as carbon source for ethanol production by Saccharomyces cerevisiae while the recycled phosphor pigment was reused in viscose filament production leading to similar mechanical properties like those measured for virgin fibers. This work presents an environmentally friendly recycling strategy of functional rayon fibers for the recovery of the two major components, namely, glucose and the pigment.

In the course of the Ioncell-P process, hemicelluloses are extracted from wood pulps by a mild treatment with an ionic liquid (IL) water mixture, and the result is a high-purity dissolving pulp. The aim of the present work is to study the influence of pulp origin concerning different wood species and pulping processes on the resulting pulp purity and yield after extraction with IL/water, while the IL is 1-ethyl-3-methylimidazolium acetate ([emim][OAc]). The raw materials were chosen from commercial alkaline kraft and acid sulfite paper and dissolving pulps prepared from both hardwood (HW) and softwood (SW). The extraction was followed by a filtration step to separate the cellulose and the hemicellulose fractions. The hemicelluloses were precipitated from the IL/water filtrate. In general, the Ioncell-P process proved to be more selective toward the removal of xylan as compared to glucomannan indicating that HW pulps are easier to purify than those of SW. It was possible to reach high alpha pulp qualities by the extraction process.